TOPIC:

Received my front piston brake caliper seals from Z! Ent. Sat., so installed them last night.

The left caliper front piston was a little pitted but not too bad. Anyway after installing new seal and cleaning up piston a little with a scuff pad ( just to make sure that there wasn't any rough or high spots ), I put everything back together. Went thru the whole bleeding process again repeatedly.

2 things that I'm noticing, First neither front caliper piston of both calipers is not moving far enough to push up against the rotor and not moving the back side of the caliper to pull up the back brake pad against the rotor. So therefore there's not any braking of the pads against the rotor?

I have bled all the air that I can see. When I release the brake caliper release valve all I'm seeing is brake fluid?

Second of all, the Left front caliper seal that I replaced with a new one , there is now a little brake fluid behind the piston Dust boot? In fact I noticed a few drips of brake fluid on the floor this morning which appears to be under the brake caliper. The dust boot looks good. I can't see any rips or tears ?

Before I upgraded to dual rotors up front ( and yes I am using the Drilled LTD rotors again. The stock solid rotor measured 7.3 mm and the drilled LTD rotors measure 5 mm. ), I was using a New after market 1/2" bore Chinese Master cylinder. I was using the stock Single brake rotor set-up and everything was working fine. It was recommended to go with a 5/8" front master and I had a used Kawasaki EX500 5/8" here. So I took it apart and cleaned it up real well. It appears to be working all right since it's pumping fluid to the calipers but maybe not since the front brake calipers are not braking the rotors?

Any Suggestions ?

Am perhaps misinterpreting, but are you saying the problem first occurred when 5 mm rotors were installed along with calipers designed for 7 mm rotors?

Good Fortune!

Patton, That is Correct. The problem occurred After I installed the thinner front brake rotors using the calipers designed for the single thicker rotor set-up?

Basically what I did was to take my 77' original caliper and move it to the right side after I turned the mounting legs of the forks around. Then I got a 78' KZ1000 left caliper which was the stock set-up for 78' and mounted it on my forks.

Before I installed the LTD thinner rotors. I was using my stock 7 mm single disc rotor and testing the Left 78' Caliper's function. Everything worked as it should.

I don't think it the other 5/8" master cylinder that I using right now is bad. For it's moving brake fluid to the calipers as it should be.

Try pumping the lever until they lock and hold. They should move in to compensate. I did the same thing but not a Chinese M/C.
Steve

Steve, That's just it. After pumping the Brake lever multiple, multiple times the brakes won't hold or pads wont's move far enough to grab the rotors?

I'm wondering if I'm using the wrong calipers as Patton suggested? I added some more information to my last Post after Patton's reply if that helps.

I'm using An older used Kawasaki EX500 5/8" master right now and as I said earlier, it appears to be working just fine. Before I did this dual rotor change out, I was using the 1/2" bore New Chinese master with the single disc rotor set-up and worked fine.

Try removing the top and pump it. The vacuum created inside the M/C might be preventing them from moving in far enough and sucking them back out causing the problem. Mine work with the thicker solid disks and the thinner drilled ones. I did have a problem with the pins sticking though. Only one side was moving. I lubed them and they freed themselves up.
Steve

Swest, Didn't help. I have always had the master cylinder reservoir cap off when bleeding the break to make sure the brake fluid didn't get down to low. Wen I had the calipers off and pulled them apart I already greased the pins and rubbers inside. There is free movement and no binding.

I would pump them, open the bleeder, then pump them again. They should be able to move in enough. TTYL
Steve

With lines bled, it seems that the master cylinder should continue pumping fluid until the caliper piston meets resistance.

swest wrote: . . . Mine work with the thicker solid disks and the thinner drilled ones. . . .

Am thinking that the stock caliper's piston protrudes further than normal in order to press the pads against the thinner rotor. But don't know what's preventing it from doing likewise in the case at hand.

The caliper's dust cover likely isn't strong enough by itself to keep the piston from protruding further than normal.

Good Fortune!

Patton, I went back to the original Chinese master cylinder I was using before which I know worked when using the original solid single disc rotor of my 77' KZ1000A. Maybe there's a possibility that the 5/8" master cylinder that I was attempting was bad and not pushing the pistons of the dual calipers against the dual LTD rotors. Well Nothing Changed ???

I don't know what to do now ?

Correct me if I'm wrong. Does the caliper piston ( solid portion ) install at the bottom of the caliper bore and ( open portion ) of the brake caliper piston face up? That's the way I have them installed but was thinking if I reversed them, would there be more brake fluid inside the open portion of the piston to exert more force therefore pushing the pistons more against the brake discs when the brake lever is applied ?

When assembled and bled, does squeezing the brake lever meet firm resistance and feel as would be expected when the brake is being applied normally?

In other words, when parked sitting still without the engine running, does squeezing the brake lever feel as if the front brake is working normally?

Good Fortune!